A study on one-dimensional consolidation of layered structured aquitard soils in a leakage system

Analytical solutions expressed using the hydraulic head for the one-dimensional consolidation of layered structured aquitard soils in a leakage system are deduced by transforming the n-layered structured soils into n + i (i = 1,2,…, n)-layered soils with gradually changing thicknesses, therein considering the behaviors of structured aquitard soils. The solutions are given in the case of instantaneous and linear decreasing confined aquifer water levels. By comparing three different examples, the effects of the structured behaviors on the consolidation characteristics are analyzed for the instantaneous decline of the confined aquifer water level.     

Effect of bedding planes on wave velocity and AE characteristics of the Longmaxi shale in China

The experimental work described in this paper was carried out in order to discover more about the effects of bedding planes on wave velocity and acoustic emission (AE) characteristics of shale. Two groups of specimens, which were collected from the Longmaxi shale outcrop in Chongqing, China and cored perpendicular and parallel to the bedding planes, were tested under uniaxial compression, and the wave velocity and AE were monitored. There were obvious differences in the acoustic characteristics of shale with different bedding plane orientations. The experimental results show that (1) the average increasing rates of P- and S-wave velocities were 39.86 and 54.41%, respectively, for the specimen with a load perpendicular to the bedding planes (Y-0). The P-wave velocity and axial strain of specimen show a marked logarithmic relationship. However, the average increasing rates of P- and S-wave velocities were 5.44 and 10.54%, respectively, for the specimen with a load parallel to the bedding planes (Y-90). The good linear relationship between P-wave velocity and axial strain before failure of specimen has been built. Generally, S-wave velocity was more sensitive to axial strain than P-wave velocity. (2) AE characteristics for Y-0 showed that a few signals → quiet period → stable increase → steep increase; for Y-90: quiet period → stable increase → sudden increase → sharp increase. The AE energy for two groups of specimens was concentrated on low and middle of amplitudes (45-80 dB), but the proportion of amplitudes (80–100 dB) and the total counts of AE for Y-0 was 1.95, 2.2 times as much as that for Y-90, respectively. The results preliminarily revealed the effect of bedding orientation on the wave velocity and AE properties of shale and may provide guidance for the improvement of acoustic logging and microseismic monitoring in the field.     

A study of dissolution and water-bearing characteristics of the restricted platform dolomite facies in the karst areas of Guizhou,China

The restricted platform facies dolomites are widely distributed in the northern and northeastern Guizhou, China, and they are the main lithology of karst groundwater and a primary target for locating drinking water resources in the province of Guizhou. The geological history and deposition environment of the restricted platform dolomite facies vary significantly across the province, making it more difficult to evaluate the dissolution and water-bearing capacity of karstic dolomites. This paper explores a quantitative approach to assessing the solubility of four typical geological strata using analytical hierarchy process (AHP) modeling. Properties including CaO/MgO, clast content, porosity, permeability and fracture density are investigated and used as the major criteria in the AHP analysis to render the rankings for solubility among the studied formations. Hydrogeological characteristics are also discussed. Overall the presented results demonstrate the feasibility of AHP as a modeling tool to provide a quantitative approach when a wide range of properties need to be considered. The explored approach can have strong implications for the exploitation and utilization of karst groundwater in Guizhou, China.     

Thermodynamic analysis of heat transfer in a wellbore combining compressed air energy storage

Compressed air energy storage (CAES) is a potential energy storage technology. The gas phase and short cycle period are two key factors affecting heat transfer loss in the wellbore of CAES. A semi-analytical solution was developed by using the convolution method considering gas movement in this study to describe the transient behavior of heat transfer with a short cycle period. The comparative analysis of the presented solution with two published solutions showed that the solution matched well with the previous solutions under steady state. Parametric studies were carried out to investigate the impact of injection rate, overall heat transfer coefficient and thermal diffusivity of the formation on heat loss in the wellbore. The results indicated that a low overall heat transfer coefficient and thermal diffusivity of the formation with an appropriate injection rate can efficiently reduce the heat loss. A hypothetical case study with a short cycle period of injection and production was conducted to demonstrate the applicability of the developed solution in CAES. The results suggest that the semi-analytical solution is applicable for heat transfer in the wellbore of CAES.     

甘肃省城市化与土地集约利用耦合协调发展

土地集约利用能够促进城市化健康发展,而城市化水平又影响着土地集约利用水平,两者的耦合协调程度是影响城市发展的关键因素。本文对甘肃省12个地级市进行实证研究,构建城市化与土地集约利用的耦合协调发展度模型,定量评价两者之间的耦合协调发展状况,并且利用地理空间分析工具进行空间聚类分析。结果表明:多数市已经从拮抗期过渡到磨合期,但是还没有进入协调期,说明甘肃省城市化与土地集约利用之间还未完全达到完全协调发展的程度;甘肃省城市化与土地集约利用的耦合协调发展度普遍较低,从2003年开始呈现出逐年扩张的趋势。     

Distribution and source of heavy metals in the surface sediments from the near-shore area,north Jiangsu Province,China

Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, ²¹⁰Pb_excess and ¹³⁷Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the I_geo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin.     

A mesoscale eddy detection method of specific intensity and scale from SSH image in the South China Sea and the Northwest Pacific

Mesoscale eddies exist almost everywhere in the ocean and play important roles in the ocean circulation of the world. These eddies may cause sound spread singular regions and bring great influences to the upwater ship and underwater aircraft. Due to the lack of hydrographic survey datasets, study of mesoscale eddies has been greatly restricted. Fortunately, satellite altimeter provided an effective way to study mesoscale eddies. An automatic detection algorithm is introduced to detect mesoscale eddies of specific intensity and spatial/temporal scale based on satellite sea surface height (SSH) data and the algorithm is applied in a strong eddy activity region: the South China Sea and the Northwest Pacific. The algorithm includes four steps. The first step is preprocessing of the SSH image, which includes elimination of error SSH data and interpolation. The second step is to detect suspected mesoscale eddies from preprocessed SSH images by dynamic threshold adjustment and morphological method, and the suspected mesoscale eddy detection includes two procedures: suspected mesoscale eddy core region detection and suspected mesoscale eddy brim extraction. The third step is to pick out mesoscale eddies satisfied with specified criteria from suspected mesoscale eddies. The criteria include three items, that is, intensity criterion, spatial scale, criterion and temporal scale criterion. The last step is algorithm performance analysis and verification. The algorithm has the capability of adaptive parameter adjustment, and can extract mesoscale eddies of interested intensity and spatial/temporal scale. The paper can provide a basis for analyzing space-time characteristics of mesoscale eddy in the South China Sea and the Northwest Pacific.     

跨越断层埋地管线地震反应研究述评

本文论述了跨越断层埋地管线地震反应研究工作概况,包括理论研究和实验研究的进展,并介绍了不同情况下采用的研究方法和建立的相应的研究模型,通过对数据结果进行整理分析,得出跨越断层埋地管线地震反应规律。同时,本文还对埋地管线研究中的一些重要参数对研究结果的影响作了详尽的阐述,提出了需进一步研究的问题和今后可能的研究发展方向。     

DLS型高精度多功能拾振器的设计与应用

文中介绍了新研制的便携式高精度多功能拾振器的技术性能、工作原理和理论计算,分析讨论了仪器的特点,给出了技术指标实测结果并进行了结构微振动记录幅值谱分析。